Measurement devices are well known to measure a predetermined parameter at a measurement location. For example, conventional thermostats typically measure the ambient temperature of a location surrounding the thermostat. Such conventional thermostats often are connected to control devices, such as heaters or coolers, so that when the measured temperature falls below a preset value the heating device will be activated or when the measured temperature rises above a different preset value the cooling device will be activated. Similarly, other measurement devices are known to measure other conditions such as smoke, fire, humidity, light, wind, vibration, noise, water level and the like. These other measurement devices may also be connected to corresponding control devices such as a sprinkler system in the case of smoke and fire detectors, and a water release valve in the case of a water level detector.
In many situations, these measurement and control devices may be located remote from those persons responsible for safekeeping of the building in which the devices are housed. For example, unattended or unoccupied buildings such as warehouses or vacant residential properties may be visited by the owners or managers of the property only on a monthly or, in some cases, only on a yearly basis. The owners or managers of such buildings, however, have an interest in determining, prior to such monthly or yearly visits, whether the condition of the building is unsatisfactory. For example, owners or managers have an interest in determining whether the temperature and other conditions of the building are being maintained at a satisfactory level so that the building and its contents will not be damaged.
Accordingly, several devices have been developed which actively notify the owner or manager of a building upon a condition within the building reaching or surpassing a predetermined set point. For example, devices are known which may be connected to a telephone line wherein the device causes the telephone line to actively call a predetermined telephone number when an alarm condition, such as the presence of smoke or fire, is detected. In addition, devices are known which allow a measurement or control device to be adjusted from a remote location by use of signals generated by a telephone or a modem.
These conventional notification devices suffer from several disadvantages. These devices often require complicated circuitry for operation and, therefore, are susceptible to breakdown or malfunction. In addition, these devices respond actively to a predetermined measurement condition such that the devices must be battery operated or directly wired to a power source. Accordingly, these devices will not function when power to the device is interrupted such as by malfunction of the power source or expiration of the batteries. A malfunctioning or a non-powered device will not actively notify a building owner or manager upon the onset of an alarm condition, thereby giving the owner or manager a false sense of security regarding the condition of the unattended building.
Accordingly, there is a need for a remote detection device that allows an owner or manager of an unattended or unoccupied building to determine the condition of the building from a remote location. Moreover, there is a need for a remote detection device wherein operation of the device is not dependent upon connection to a power source or the operation of batteries.